Torque-off collars are threaded nut-like devices which have a driver section engaged by a torque tool that shears off from a driver section when a predetermined torque is applied. the driver section of the collar then remains set on a pin to which it is engaged, set to the predetermined torque.
The classical torque-off collar is shown in U.S. Pat. No. 2,940,495, issued to George S. Wing. In this collar, the drive section is hexagonal so as to be engagable by a wrench or socket. It is customary for the size of the hexagonal section to differ from size to size of the collar, and this results in the need to change wrenches or sockets each time a different size of collar is set.
Also, the wrench and the collar must be properly aligned rotationally in order for the wrench to engage the flats on the drive section. This requires equipment or manipulation to bring them into alignment. Feed-in sockets are known for this purpose, and of course the operator can himself rotate the wrench or the collar to make the necessary alignment.
The above situations are acceptable for general assembly work, and the system is in widespread usage. Usually a large number of collars of the same size will be driven sequentially so that changing of sockets and the use of a lead-in socket are reasonable expedients. Also, if the alignment of the collar and wrench is not provided for by special devices, the minor nuisance or delay invovled is generally acceptable.
The same is not true for robotic installations. Such installations are programmed in exquisite detail, and any manipulation such as socket changes or alignment efforts from one collar size to another complicates the program and decreases the capacity of the system. In this sense, a robotic installation is an example of a universal installation, wherein a large range of sizes and head sizes can be set by a single tool system.
It is an object of this invention to provide a torque-off collar with a driver section of such dimensions that the samesized driver section can be used for other collar sizes also. It is another object to provide a driver section which does not require a special angular alignment between the driver and the drive section. A robotic driver can therefore randomly engage the drive section, and can drive a wide range of collar sizes without change of sockets or wrenches. Accordingly the collar of this invention is advantageously adapted for use in robotic systems.